Beijer-electronics SCOM RBC EN Uživatelský manuál stáhnout pdf (Strana 10)

Protocol Description and Timings

10 Beijer Electronics, MAEN993

Conditions for Response Message

The conditions for a response message generated by the Beijer Electronics RBC are

described below:

Delayed Response

If a Beijer Electronics RBC receives an SCOM message with a broadcast address from

the RS485 interface and the command is completed, the generated response message

is sent after a delay time. This is required, because many devices can be attached to

the RS485 bus, but only one device can claim the line for its communication. The

delay guarantees that each response message is sent one after one, even if all devices

have received the broadcast message and processed it at the same time, avoiding a col-

lision on the RS485 bus.

The length of the delay time depends on the device address and maximum length of

a response message, and is calculated according to the following formula:

Interface Address condition Command status Response

RS232 Address does not match

device address

not EXECUTED No response

Address matches device

address

if COMPLETED ACK

if FAILED NAK

Address is Broadcast

address (0xFF)

if COMPLETED ACK

if FAILED NAK

RS485 Address does not match

device address

not EXECUTED No response

Address matches device

address

if COMPLETED ACK

if FAILED NAK

Address is Broadcast

address (0xFF)

if COMPLETED Delayed ACK

if FAILED No response

USB Address does not match

device address

not EXECUTED No response

Address matches device

address

if COMPLETED ACK

if FAILED NAK

Address is Broadcast

address (0xFF)

if COMPLETED ACK

if FAILED NAK

(2.5 + Lr) x 10 x N

Te =

Te: Broadcast command response [s]

Lr: Maximum length of response message

N: Device address + 1

b: Baud rate [bits/second]

1 2 ... 5 6 7 8 9 10 11 12 13 14 15 ... 63 64

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